This proposal is intended to cover a five-year period of electrophysiological and biochemical research on the sensory and neuroendocrine basis of olfactory discrimination in hamsters. The particular focus of attention is upon pheromone-like odors produced by the animals themselves and exerting an influence upon ethologically- significant behavior patterns such as reproduction, territoriality and social dominance, and upon the neuroendocrine, mechanisms underlying such behaviors. The specific objectives of the proposed research include (1) identification of naturally-occurring odors, (2) analysis of their effects upon the activity of single units in the olfactory bulb and in forebrain structures involved in olfactory discrimination, endocrine regulation, and the expression of social behaviors, (3) study of the mechanisms by which these odors affect the hamster's endocrine secretions and social behavior, and (4) determination of the extent to which the temporal parameters of sensory input relative to intrinsically rhythmical activity in the limbic system affect the transmission of olfactory information to the diencephalon. It is hoped that the proposed experiments will shed light upon (a) the interrelationships among body odors, olfactory unit activity, and neuroendocrine control mechanisms, and (b) the morphological and functional connections among brain mechanisms involved in such crucial behavioral activities as reproduction and socialization. The stereotyped sequence of movements which the hamster employs to sample its olfactory environment, the clearcut effects of odors on its social behavior and endocrine activity, and its dependence on gonadal hormones for support of its sexual predispositions make the hamster an ideal subject for our proposed studies.